Line of Credit, Current Line of Credit, Current Defined benefit plan, target allocation percentage of assets Defined Benefit Plan, Plan Assets, Target Allocation, Percentage Undistributed Earnings Allocated To Common Stockholders Undistributed Earnings Allocated To Common Stockholders The earnings that is allocated to common stock to the extend that each stockholder may share in the earnings as if all the earnings for the period has been distributed. Contingencies Commitments and Contingencies Disclosure [Text Block] Interest Rate Swap Interest Rate Cash Flow Hedge Asset at Fair Value Deferred income tax liability Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities Investments Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Advance Related To Kaplan University Transaction Advance Related To Kaplan University Transaction Advance related to Kaplan University Transaction. Redeemable Noncontrolling Interest, Equity, Common, Redemption Value Redeemable Noncontrolling Interest, Equity, Common, Redemption Value Measurement period adjustments Goodwill, Purchase Accounting Adjustments Proceeds from sales of marketable equity securities Proceeds from Sale and Maturity of Marketable Securities Amortization of Intangible Assets Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract] Statistical Measurement [Domain] Statistical Measurement [Domain] Liabilities and Equity Liabilities and Equity [Abstract] Total Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Less Noncontrolling Interest Investment Manager 2 [Member] Investment Manager 2 [Member] Investment Manager 2 [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Distribution to noncontrolling interest Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders Security Exchange Name Security Exchange Name Issuance of borrowings Proceeds from Issuance of Long-term Debt Aggregate purchase price, net of cash acquired Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Less Noncontrolling Interest, Net Of Cash Received Amount recognized as of the acquisition date for the assets, including goodwill, in excess of (less than) the aggregate liabilities assumed, less the noncontrolling interest in the acquiree, net of cash received. Total Current Liabilities Liabilities, Current March 22, 2018 through June 30, 2023 [Member] March 22, 2018 through June 30, 2023 [Member] Period of time March 22, 2018 through June 30, 2023 for which the TOSA term applies (first 5 years) Reclassification out of Accumulated Other Comprehensive Income [Member] Reclassification out of Accumulated Other Comprehensive Income [Member] Transferred over Time [Member] Transferred over Time [Member] Variable Rate [Domain] Variable Rate [Domain] Add: Additional undistributed earnings due to dilutive stock options Additional Undistributed Earnings Due To Dilutive Stock Options The earnings that is allocated to common stock due to the dilutive effect of stock options in diluted earnings per share. Number of finalized program reviews Number Of Finalized Program Reviews Number of finalized program reviews. Issuance of Class B common stock, net of restricted stock award forfeitures Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures Assets Assets [Abstract] Contract costs capitalized during the period Contract Costs Capitalized During the Period Capitalized contract costs associated with new contracts entered into during the period. Investment, Name [Axis] Investment, Name [Axis] Accumulated Other Comprehensive Income (Loss) Comprehensive Income (Loss) Note [Text Block] Transition and Operations Support Agreement Renewal Periods Transition and Operations Support Agreement Renewal Periods Transition and Operations Support Agreement Renewal Periods after initial 30 year term Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Five-Year Credit Agreement dated May 30, 2018 [Member] Five-Year Credit Agreement dated May 30, 2018 [Member] Five-Year Credit Agreement dated May 30, 2018 Class B Common Stock [Member] Common Class B [Member] Common Class B [Member] Other Temporary Equity, Other Changes Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Accelerated depreciation of property, plant and equipment Restructuring and Related Cost, Accelerated Depreciation New Accounting Pronouncements or Change in Accounting Principle [Line Items] New Accounting Pronouncements or Change in Accounting Principle [Line Items] Deferred Revenue Deferred Revenue Preferred Stock Preferred Stock, Value, Issued Other assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Assets Amount of other assets acquired at the acquisition date. Deferred Revenue, Period Decrease Percentage Deferred Revenue, Period Increase (Decrease) Percentage Deferred Revenue, Period Increase (Decrease) Percentage Property, plant and equipment Tangible Asset Impairment Charges Schedule of Earnings Per Share, Basic and Diluted, Including Two Class Method [Line Items] Schedule of Earnings Per Share, Basic and Diluted, Including Two Class Method [Line Items] [Line Items] for Disclosures pertaining to an entity's basic and diluted earnings per share. Operating Expenses Operating Expenses FCC licenses [Member] Operating and Broadcast Rights [Member] Vehicle Floor Plan Facility [Member] Vehicle Floor Plan Facility [Member] Vehicle Floor Plan Facility [Member] Higher Education [Member] Higher Education [Member] Higher Education [Member] Other Liabilities Other Liabilities, Noncurrent Deferred Income Taxes Deferred Income Tax Assets, Net Other Indebtedness [Member] Other Indebtedness [Member] Other Indebtedness [Member] AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] Work-in-process Inventory, Work in Process, Net of Reserves Effect Of Currency Exchange Rate Change Effect of Exchange Rate on Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Fair Value Measurements [Abstract] Fair Value Measurements [Abstract] Fair Value Measurements [Abstract] CARES Act Fund [Axis] CARES Act Fund [Axis] CARES Act Fund Measurement Frequency [Domain] Measurement Frequency [Domain] Interest Rate on Advance to Minority Shareholder Interest Rate on Advance to Minority Shareholder Interest Rate on Advance to Minority Shareholder Clyde's Restaurant Group [Member] Clyde's Restaurant Group [Member] Clyde's Restaurant Group Minimum percentage of plan assets considered as significant concentrations in pension plans Concentration Risk, Percentage Residential Healthcare Michigan hospital joint venture [Member] Residential And Michigan Hospital Joint Venture [Member] Residential and a Michigan hospital joint venture [Member] Statement [Line Items] Statement [Line Items] Number of businesses disposed Number Of Businesses Disposed The number of businesses disposed of by the entity during the period. Class of Stock [Domain] Class of Stock [Domain] Debt Instrument, Term Debt Instrument, Term Accounts Receivable Loans, Notes, Trade and Other Receivables Disclosure [Text Block] Statement [Table] Statement [Table] Interest cost Defined Benefit Plan, Interest Cost Statistical Measurement [Axis] Statistical Measurement [Axis] Income Taxes [Line Items] Income Taxes [Line Items] Income Taxes [Line Items] Amortization of lease right-of-use asset Operating Lease, Right-of-Use Asset, Amortization Expense Equity Funds [Member] Equity Funds [Member] Other current assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Other Early Retirement Program Expense [Domain] Early Retirement Program Expense [Domain] -- None. No documentation exists for this element. -- Entity Small Business Entity Small Business Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Debt Debt Disclosure [Text Block] Prepaid expenses Prepaid Expense, Current Prospective Adoption of New Accounting Pronouncements [Table] Prospective Adoption of New Accounting Pronouncements [Table] Number of investment companies actively managing plan assets Number Of Investment Companies Managing Plan Assets The number of investment companies actively managing plan assets. Government Relief, CARES Act Government Relief, CARES Act Amount received from the government as relief under the CARES Act Percent allocated to common stockholders Percentage Of Undistributed Earnings Allocated To Common Stockholders Represents the percentage allocation of undistributed earnings to common stockholders. Amendment Flag Amendment Flag Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Reallocation Goodwill, Transfers Corporate Office [Member] Corporate, Non-Segment [Member] Transition and Operations Support Agreement Initial Term Transition and Operations Support Agreement Initial Term Transition and Operations Support Agreement Initial Term Other Comprehensive Income (Loss), Before Tax Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract] Measurement Frequency [Axis] Measurement Frequency [Axis] Initial Application Period Cumulative Effect Transition [Axis] Initial Application Period Cumulative Effect Transition [Axis] Expected return on assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets Undistributed earnings Undistributed Earnings, Basic Contract with Customer, Duration [Axis] Contract with Customer, Duration [Axis] Number Of Preliminary Program Review Reports received Number Of Preliminary Program Review Reports Received The number of Preliminary Program Review Reports received. 2014 to 2018 [Member] 2014 to 2018 [Member] 2014 to 2018 [Member] Kaplan Share of Purdue University Global Revenue Kaplan Share of Purdue University Global Revenue Percentage representing Kaplan's fee based on Purdue University Global Revenue Selling, general and administrative Selling, General and Administrative Expenses The aggregate total costs related to selling a firm's product and services, as well as all other general and administrative expenses. Direct selling expenses (for example credit, warranty, and advertising) are expenses that can be directly linked to the sale of specific products. Indirect selling expenses are expenses that cannot be directly linked to the sale of specific products, for example telephone expenses, Internet, and postal charges. General and administrative expenses include salaries of non-sales personnel, rent, utilities, communication, etc. Also includes expenses such as bad debt expense, and gain (loss) on disposition of assets. Income Statement Location [Domain] Income Statement Location [Domain] Cash Flows from Financing Activities Net Cash Provided by (Used in) Financing Activities [Abstract] Selling, General and Administrative Expense Selling, General and Administrative Expense Inventories and contracts in progress Inventories and contracts in progress Inventory, Net of Allowances, Customer Advances and Progress Billings Deferred Charges and Other Assets (includes $4,509 and $0 of restricted cash) Other Assets, Noncurrent Kaplan University Transaction Termination Fee Kaplan University Transaction Termination Fee Percent of Purdue Global University revenue for preceding 12 month period to be paid to terminate the Transition and Operations Support Agreement Total Financial Liabilities Financial Liabilities Fair Value Disclosure Percentage of Distributions Available to Common Unit Holders Percentage of Distributions Available to Common Unit Holders Percentage of distributions available to common unit holders Total Assets Assets Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill) Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill) Organization, Basis of Presentation and Recent Accounting Pronouncements Organization, Consolidation, Basis of Presentation, Business Description and Accounting Policies [Text Block] Indefinite-lived intangible assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Indefinite-Lived Intangible Assets Item Effected [Line Items] Item Effected [Line Items] Amortization of prior service cost (credit) Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Subsequent Event Type [Axis] Subsequent Event Type [Axis] UK Pathways [Member] UK Pathways [Member] UK Pathways [Member] Total Cost Equity Securities, FV-NI, Cost Reclassification out of Accumulated Other Comprehensive Income [Axis] Reclassification out of Accumulated Other Comprehensive Income [Axis] Gimlet Media [Member] Gimlet Media [Member] Gimlet Media [Member] Acquisitions and Dispositions of Businesses Mergers, Acquisitions and Dispositions Disclosures [Text Block] Pinnacle Bank Loan & Security Agreement [Member] Pinnacle Bank Loan & Security Agreement [Member] Pinnacle Bank Loan & Security Agreement [Member] Other [Member] Other Intangible Assets [Member] Net unrealized gains in earnings from marketable equity securities still held at the end of the period Equity Securities, FV-NI, Unrealized Gain (Loss) Cash and cash equivalents Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents Framebridge [Member] Framebridge [Member] Framebridge [Member] Total Liabilities Liabilities Investments in equity affiliates, cost method and other investments Payments To Acquire Equity Method Cost Method Investments And Other Investments The cash outflow associated with the purchase of equity method investments, which are investments in joint ventures and entities in which the entity has an equity ownership interest normally of 20 to 50 percent and exercises significant influence, cost method investments or other investments, not including marketable equity securities. Retirement Plan Type [Axis] Retirement Plan Type [Axis] Other Businesses [Member] Other Segments [Member] Databases and Technology [Member] Database Rights [Member] Diluted average number of common shares outstanding in shares Weighted Average Number Of Potentially Dilutive Shares Outstanding The weighted average number of shares outstanding that could potentially dilute basic EPS. KIHL [Member] KIHL [Member] KIHL [Member] Purchase of noncontrolling interest Payments for Repurchase of Redeemable Noncontrolling Interest Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Level 1 Fair Value, Inputs, Level 1 [Member] Inventories Increase (Decrease) in Inventories Operating Income before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets. Operating Income before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets. Operating Income before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets. Other assets and other liabilities, net Increase (Decrease) in Other Operating Assets and Liabilities, Net Interest Expense, Net Interest Expense, Net Interest Income (Expense), Net Additional Paid-in Capital [Member] Additional Paid-in Capital [Member] Celtic Healthcare Allegheny Health Network Joint Venture [Member] CelticHealthcareAlleghenyHealthNetworkJointVenture [Member] A joint venture formed between Celtic Healthcare and Allegheny Health Network Summary of non-operating income Schedule of Other Nonoperating Income (Expense) [Table Text Block] New Accounting Pronouncement, Early Adoption [Table] New Accounting Pronouncement, Early Adoption [Table] Acquisitions And Dispositions [Abstract] Acquisitions And Dispositions [Abstract] Acquisitions and Dispositions Other Other Operating Activities, Cash Flow Statement Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] Other receivables Other Receivables Purchase of redeemable noncontrolling interest Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests Income Tax Disclosure [Abstract] Income Tax Disclosure [Abstract] Aggregate Purdue University Global cash operating losses Aggregate Purdue University Global Cash Operating Losses Aggregate Purdue University Global cash operating losses threshold for option to terminate Transition and Operations Support Agreement Operating Costs and Expenses [Abstract] Operating Costs and Expenses [Abstract] Schedule of Goodwill [Table] Schedule of Goodwill [Table] Income Before Income Taxes Income Before Income Taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Transaction Type [Domain] Transaction Type [Domain] Transaction Type [Domain] Net Actuarial Gain [Member] Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member] Investments in certain businesses, net of cash acquired Purchase Price Net of Cash Payments to Acquire Businesses, Net of Cash Acquired Total Debt Debt, Long-term and Short-term, Combined Amount Percentage of interest acquired Business Acquisition, Percentage of Voting Interests Acquired Add: Effect of dilutive stock options (shares) Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Proceeds from exercise of stock options Proceeds from Stock Options Exercised Summary of Segment Reporting Information, by Operating Segment Schedule of Segment Reporting Information, by Segment [Table Text Block] Operating Expense [Member] Operating Expense [Member] Inventory, Net of Allowances, Customer Advances and Progress Billings [Abstract] Inventory, Net of Allowances, Customer Advances and Progress Billings [Abstract] Income Statement [Abstract] Income Statement [Abstract] AOCI Attributable to Parent [Member] AOCI Attributable to Parent [Member] Floor plan assistance Vehicle Floor Plan Facility Assistance The amount of assistance received from the manufacturers recognized as a reduction of operating expenses. Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Period of Transition Operations and Support Agreement [Domain] Period of Transition Operations and Support Agreement [Domain] [Domain] for Period of Transition Operations and Support Agreement [Axis] Disposal Groups, Including Discontinued Operations [Table] Disposal Groups, Including Discontinued Operations [Table] Purdue University Global [Member] Purdue University Global [Member] Purdue University Global Use of Estimates in the Preparation of the Condensed Consolidated Financial Statements Use of Estimates, Policy [Policy Text Block] AOCI Including Portion Attributable to Noncontrolling Interest [Member] AOCI Including Portion Attributable to Noncontrolling Interest [Member] Business Segments [Table] Business Segments [Table] Business Segments [Table] Advances to Affiliate Advance to Minority Shareholder Advance to Minority Shareholder Gross unrealized gains Equity Securities FV-NI, Accumulated Gross Unrealized Gain Amount of unrealized gain on investment on equity security measured at fair value with change in fair value recognized in net income (FV-NI). Balance of costs to obtain a contract Capitalized Contract Cost, Net Kaplan University Transaction [Member] Kaplan University Transaction [Member] Kaplan University Transaction [Member] Purchases of property, plant and equipment Payments to Acquire Property, Plant, and Equipment Consolidation Items [Domain] Consolidation Items [Domain] Loss on Guarantor Lease Obligations Loss on Guarantor Lease Obligations The amount of loss recognized on guarantor lease obligations. Business Combination, Contingent Consideration, Liability Contingent consideration liabilities Business Combination, Contingent Consideration, Liability Goodwill and Other Intangible Assets Goodwill and Intangible Assets Disclosure [Text Block] Kaplan [Member] Kaplan [Member] Kaplan [Member] Equity in earnings of affiliates, net Income (Loss) from Equity Method Investments Percentage of total plan assets Defined Benefit Plan Assets Allocation (Percent) Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage Current liabilities Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities Reclassification out of Accumulated Other Comprehensive Income [Domain] Reclassification out of Accumulated Other Comprehensive Income [Domain] Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Accumulated impairment losses, beginning balance Accumulated impairment losses, ending balance Goodwill, Impaired, Accumulated Impairment Loss Lease right-of-use assets Operating Lease, Impairment Loss Schedule of Inventories and Contracts in Progress Schedule of Inventory, Current [Table Text Block] Other Comprehensive Income (Loss) before Reclassifications, Tax Other Comprehensive Income (Loss) before Reclassifications, Tax Total Fair Value Marketable equity securities Equity Securities, FV-NI Entity [Domain] Entity [Domain] Restructuring and Related Costs Restructuring and Related Costs [Table Text Block] Acquisitions Goodwill, Acquired During Period Goodwill [Line Items] Goodwill [Line Items] Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Deferred revenue Increase (Decrease) in Deferred Revenue Restricted cash Restricted Cash and Cash Equivalents Subsegments Consolidation Items [Axis] Subsegments Consolidation Items [Axis] Other (loss) gain, net Other Nonoperating Gains (Losses) Series of Individually Immaterial Business Acquisitions [Member] Series of Individually Immaterial Business Acquisitions [Member] Kaplan Four-Year Credit Agreement dated July 14, 2016 [Member] Kaplan Four Year Credit Agreement Dated July 14, 2016 [Member] Kaplan Four Year Credit Agreement Dated July 14, 2016 [Member] Restricted Stock Awards [Member] Restricted Stock [Member] Finished goods Inventory, Finished Goods, Net of Reserves Accounts receivable Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables Current portion of lease liabilities Operating Lease, Liability, Current July 1, 2022 through June 30, 2027 [Member] July 1, 2022 through June 30, 2027 [Member] Period of time July 1, 2022 through June 30, 2027 for which the TOSA term applies (Years 5-9) Fair Value Measurements Fair Value Disclosures [Text Block] Antidilutive Weighted Average Restricted Stock and Options Antidilutive Weighted Average Restricted Stock [Table Text Block] [Table Text Block] for Additional shares excluded in the calculation of diluted EPS as a result of the antidilutive effect of restricted stock using the treasury stock method. Interest Rate Swap [Member] Interest Rate Swap [Member] Minimum Term of Contract Minimum Term of Contract Minimum Term of Contract Entity Registrant Name Entity Registrant Name Subsequent Event Type [Domain] Subsequent Event Type [Domain] Cumulative foreign currency translation adjustment Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax Business Acquisition [Line Items] Business Acquisition [Line Items] Impairment of goodwill and other long-lived assets Goodwill and intangible asset impairment charge Asset Impairment Charges Intersegment Elimination [Member] Intersegment Eliminations [Member] Debt Issuance Costs, Net Unamortized debt issuance costs Debt Issuance Costs, Net Recipient of Consideration [Axis] Recipient of Consideration [Axis] Recipient of Consideration Kaplan Corporate and Other [Member] Kaplan Corporate and Other [Member] Kaplan Corporate And Other [Member] Pension and other postretirement plans: Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax [Abstract] Equity Securities [Member] Equity Securities [Member] Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Investments [Abstract] Investments [Abstract] Adjustments for New Accounting Pronouncements [Axis] Accounting Standards Update [Axis] Restricted Cash, Noncurrent Restricted Cash, Noncurrent Weighted average stock options Antidilutive Options Additional shares excluded in the calculation of diluted EPS as a result of the antidilutive effect of options using the treasury stock method. Operating lease cost Operating Lease Abandonment Cost Amount of lease cost, calculated by allocation of remaining cost of lease over remaining lease term, due to early abandonment of lease in part of restructuring plan. Accounting Standards Update 2016-02 [Member] Accounting Standards Update 2016-02 [Member] Entity Address, Postal Zip Code Entity Address, Postal Zip Code Red Marker [Member] Red Marker [Member] Red Marker [Member] Annual Purdue University Global Cash Operating Losses Annual Purdue University Global Cash Operating Losses Annual Purdue University Global cash operating losses threshold for option to terminate Transition and Operations Support Agreement Summary of Other Comprehensive Income (Loss) Comprehensive Income (Loss) [Table Text Block] Goodwill, Net Goodwill Goodwill, net, beginning balance Goodwill, net, ending balance Goodwill Education [Member] Education [Member] Education [Member] Business Acquisition, Transaction Costs Business Acquisition, Transaction Costs Timing of Transfer of Good or Service [Axis] Timing of Transfer of Good or Service [Axis] Graham Holdings Company Common Stockholders: Income Per Share From Continuing Operations To Common Stockholders [Abstract] Income Per Share From Continuing Operations To Common Shareholders. Dividends declared per common share Common Stock, Dividends, Per Share, Declared Mandatorily redeemable noncontrolling interest Mandatorily Redeemable Noncontrolling Interest Fair Value Disclosure Fair value of the Noncontrolling interest that an entity is required to redeem for cash or other assets at a fixed or determinable date or upon the occurrence of an event. Change in redemption value of redeemable noncontrolling interests Temporary Equity, Change in Redemption Value Change in temporary equity during the period as a result of a change in the redemption value of redeemable noncontrolling interest. Investment Manager 1 [Member] Investment Manager 1 [Member] Investment Manager 1 [Member] Debt Instrument, Face Amount Debt Instrument, Face Amount Less: Net losses (gains) in earnings from marketable equity securities sold and donated Equity Securities, FV-NI, Realized Gain (Loss) Television Broadcasting [Member] Television Broadcasting [Member] Television Broadcasting [Member] Other current assets Other Assets, Current Changes in Carrying Amount of Goodwill Schedule of Goodwill [Table Text Block] Gain (Loss) on Marketable Equity Securities Gain (Loss) on Securities [Table Text Block] Berkshire Hathaway Common Stock [Member] Berkshire Hathaway Common Stock [Member] Berkshire Hathaway Common Stock [Member] Denominator for diluted earnings per share (shares) Weighted Average Number of Shares Outstanding, Diluted Number of Operating Segments Number of Operating Segments Provider Relief Fund [Member] Provider Relief Fund [Member] Provider Relief Fund under the CARES Act Debt Disclosure [Abstract] Debt Disclosure [Abstract] Inventory, Current [Table] Inventory, Current [Table] Net Cash (Used in) Provided by Financing Activities Net Cash Provided by (Used in) Financing Activities Repayments of borrowings Repayments of Long-term Debt Special separation benefit expense Non-operating pensions and postretirement benefit income, net Defined Benefit Plan, Cost of Providing Special and Contractual Termination Benefits Deferred Revenue [Domain] Deferred Revenue [Domain] Depreciation, amortization and goodwill and other long-lived asset impairments Depreciation, Depletion, Amortization And Impairment The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets, including write-downs for impairments. Revenue, Remaining Performance Obligation, Amount Revenue, Remaining Performance Obligation, Amount Redeemable noncontrolling interest Redeemable noncontrolling interest Redeemable Noncontrolling Interest, Equity, Other, Fair Value Common stock Common Stock, Value, Issued Amortized Intangible Assets [Line Items] Finite-Lived Intangible Assets [Line Items] Document Fiscal Year Focus Document Fiscal Year Focus Deferred income tax asset Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Assets Estimated amortization of intangible assets, 2022 Finite-Lived Intangible Asset, Expected Amortization, Year Two Dividends paid Payments of Ordinary Dividends Capitalized Contract Cost Capitalized Contract Cost [Table Text Block] Gain on cost method investments Equity Securities without Readily Determinable Fair Value, Upward Price Adjustment, Annual Amount Current portion of long-term debt Less: current portion Long-term Debt, Current Maturities Entity Current Reporting Status Entity Current Reporting Status Proceeds from Sale of Equity Method Investments Proceeds from Sale of Equity Method Investments Comprehensive Income Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Gain related to contingent consideration Gain related to contingent consideration Gain Related to Contingent Consideration Contingent consideration gain related to the sale of a business. Transition and Operations Support Agreement Buy-Out Option Eligible Year Transition and Operations Support Agreement Buy-Out Option Eligible Year Transition and Operations Support Agreement Buy-Out Option Eligible Year Commercial note payable Commercial note Notes Payable to Bank Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Maximum Term of Contract Maximum Term of Contract Maximum Term of Contract Total lease liabilities Operating Lease, Liability Long-Term Debt Total Long-Term Debt Long-term Debt, Excluding Current Maturities Segment Reporting [Abstract] Segment Reporting [Abstract] Debt Instrument [Line Items] Debt Instrument [Line Items] Total Common Stockholders' Equity Stockholders' Equity Attributable to Parent Acquisition purchase price Business Combination, Consideration Transferred Entity Address, City or Town Entity Address, City or Town Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Purchase of redeemable noncontrolling interest Equity effect of redemption of redeemable noncontrolling interest Equity effect of redemption of redeemable noncontrolling interest Accounts payable and accrued liabilities Accounts Payable and Accrued Liabilities, Current Type of Adoption [Domain] Accounting Standards Update [Domain] Other Intangible Assets Schedule of Finite and Indefinite Lived Intangible Assets [Table Text Block] Schedule of Finite and Indefinite Lived Intangible Assets [Table Text Block] Indefinite-lived Intangible Assets [Axis] Indefinite-lived Intangible Assets [Axis] Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items] Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] Line of Credit Facility, Interest Rate at Period End Line of Credit Facility, Interest Rate at Period End Liabilities Liabilities [Abstract] Amount of Priority Payment Per Year Beyond Costs Amount of Priority Payment Per Year Beyond Costs Amount of priority payment made to Purdue University Global beyond costs before any payment to Kaplan Lease Right-of-Use Assets Business Combination, Recognized Identifiable Asset Acquired and Liability Assumed, Lease Right-of-Use Asset Amount of lease right of use assets assumed in business combination Estimated amortization of intangible assets, 2023 Finite-Lived Intangible Asset, Expected Amortization, Year Three Gain on sale of cost method investments Equity Securities, FV-NI, Realized Gain Percentage of Additional Ownership Available to be Acquired Percentage of Additional Ownership Available to be Acquired The percentage of additional ownership available to be acquired by the minority shareholder. Investment, Name [Domain] Investment, Name [Domain] Other Comprehensive Income (Loss), Net of Tax Other comprehensive income (loss), net of income taxes Other Comprehensive Income (Loss), Net of Tax Other Comprehensive Income (Loss), Net of Tax Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Total Current Assets Assets, Current Comprehensive (income) loss attributable to noncontrolling interests Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest Per Share Information Attributable to Graham Holdings Company Common Stockholders Earnings Per Share [Abstract] Total Restructuring Costs Include in Segment Income (Loss) from Operations Restructuring Charges Income Tax Authority, Name [Axis] Income Tax Authority, Name [Axis] Amortization of net prior service cost (credit) included in net income Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax Pension and Other Postretirement Plans [Member] Unrealized Gain on Pensions and Other Postretirement Plans [Member] Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Gain on sale of businesses Gain (Loss) on Disposition of Business Noncontrolling interest Business Combination, Acquisition of Less than 100 Percent, Noncontrolling Interest, Fair Value Issuance of noncontrolling interest Noncontrolling Interest, Increase from Subsidiary Equity Issuance Document Fiscal Period Focus Document Fiscal Period Focus Total fixed interest rate of derivative Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate Numerator for diluted earnings per share Net Income (Loss) Available to Common Stockholders, Diluted GHC One [Member] GHC One [Member] GHC One [Member] Investments in marketable equity securities and other investments Investments In Marketable Equity Securities And Other Investments Total debt and equity financial instruments including: (1) securities held-to-maturity, (2) trading securities, and (3) securities available-for-sale which are intended to be held for less than one year or the normal operating cycle, whichever is longer. Also includes other current investments such as mutual funds. Entity Filer Category Entity Filer Category Common Stock [Member] Common Stock [Member] Foreign Currency Translation Adjustment [Member] Cumulative Foreign Currency Translation Adjustment [Member] Accumulated Foreign Currency Adjustment Attributable to Parent [Member] Product and Service [Domain] Product and Service [Domain] Graham Healthcare Group [Member] Healthcare [Member] Graham Healthcare Group [Member] Graham Healthcare Group [Member] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Return of investment in equity affiliates Proceeds from Equity Method Investment, Distribution, Return of Capital U.S. stock index fund [Member] Equity Funds, US [Member] An investment that pools funds from many investors to invest in a combination of underlying investments, primarily equity investments, domiciled in United States of America (US). Summary of Amounts and Line Items of Reclassifications Out of Accumulated Other Comprehensive Income (Loss) Reclassification out of Accumulated Other Comprehensive Income [Table Text Block] Basis of Presentation Consolidation, Subsidiaries or Other Investments, Consolidated Entities, Policy [Policy Text Block] Mandatorily Redeemable Noncontrolling Interest Financial Instruments Subject to Mandatory Redemption, Settlement Terms, Share Value, Amount, Noncurrent Less: Dividends paid-common stock outstanding and unvested restricted shares Dividends Paid Common Stock And Share-based Compensation-Cash Amount of paid and unpaid common stock dividends declared with the form of settlement in cash and amount of paid and unpaid cash dividends declared and applicable to holders of share-based compensation, for example, but not limited to, non-vested shares, stock options, or restricted stock units. Investment Managers [Axis] Investment Managers [Axis] Investment Managers [Axis] Unusual or Infrequent Item, or Both [Domain] Unusual or Infrequent Item, or Both [Domain] Interest rate Debt Instrument, Interest Rate, Stated Percentage Dividends declared Dividends Payable, Current Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period Class A Common Stock [Member] Common Class A [Member] Floor plan payables Floor plan payables Vehicle floor plan payable Vehicle Floor Plan Facility Payable The amount borrowed to finance the purchase of specific vehicle inventories. Net Increase (Decrease) in Cash and Cash Equivalents and Restricted Cash Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Pinnacle Bank Term Loan [Member] Pinnacle Bank Term Loan [Member] Term loan with Pinnacle Bank Stock Option Plan [Member] Share-based Payment Arrangement, Option [Member] Automotive [Member] Automotive [Member] Automotive [Member] Subsegments Consolidation Items [Domain] Subsegments Consolidation Items [Domain] Ownership [Domain] Ownership [Domain] Kaplan University [Member] Kaplan University [Member] -- None. No documentation exists for this element. -- Cost method investments Equity Securities without Readily Determinable Fair Value, Amount Total Equity As of As of Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Organization, Consolidation and Presentation of Financial Statements Disclosure Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Capital in excess of par value Additional Paid in Capital Estimated amortization of intangible assets, 2021 Finite-Lived Intangible Asset, Expected Amortization, Year One Operating Revenues Revenues Class of Stock [Axis] Class of Stock [Axis] Debt [Table] Debt [Table] Schedule of all debt, including both short term and long term. New Accounting Pronouncements or Change in Accounting Principle [Table] Accounting Standards Update and Change in Accounting Principle [Table] Diluted net income per common share in dollars per share Diluted income per common share in dollars per share Earnings Per Share, Diluted Professional (U.S.) [Member] Kaplan Professional [Member] Kaplan Professional [Member] Components of Debt Schedule of Debt [Table Text Block] Depreciation of property, plant and equipment Depreciation Entity Address, Address Line One Entity Address, Address Line One Non-compete Agreements [Member] Noncompete Agreements [Member] Applicable Years [Axis] Applicable Years [Axis] Applicable Years [Axis] Entity Emerging Growth Company Entity Emerging Growth Company Indefinite-Lived Intangible Assets Indefinite-lived Intangible Assets (Excluding Goodwill) Pro Forma Operating Revenues Business Acquisition, Pro Forma Revenue (Benefit from) provision for deferred income taxes Deferred Income Tax Expense (Benefit) Residential Home Health Illinois [Member] Residential Home Health Illinois [Member] Residential Home Health Illinois [Member] Loss Contingency, Loss in Period Loss Contingency, Loss in Period Accumulated Amortization Finite-Lived Intangible Assets, Accumulated Amortization Maximum [Member] Maximum [Member] Management Fee Management Fee Management fee payable by the Company in connection with management services provided under the management services agreement Noncontrolling Interest [Member] Noncontrolling Interest [Member] Add: Dividends paid-common stock outstanding Dividends, Common Stock, Cash Cash flow hedges gain (loss) Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, before Tax Effective Income Tax Rate Effective Income Tax Rate Reconciliation, Percent Her Majesty's Revenue and Customs (HMRC) [Member] Her Majesty's Revenue and Customs (HMRC) [Member] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Estimated credit losses Accounts Receivable, Allowance for Credit Loss Derivative, Basis Spread on Variable Rate Derivative, Basis Spread on Variable Rate Other Postretirement Benefit Plan, Defined Benefit [Member] Other Postretirement Plans [Member] Other Postretirement Benefits Plan [Member] Trading Symbol Trading Symbol Revenue from Related Parties Revenue from Related Parties Cumulative realized gain (loss) on marketable securities Marketable Securities, Realized Gain (Loss) Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Restructuring, Settlement and Impairment Provisions Restructuring, Settlement and Impairment Provisions Net pension benefit Net Periodic Cost (Benefit) Net Periodic Benefit For Defined Benefit Pension Plans Excluding Early Retirement Program, Special Separation Benefit Expense, Curtailment And Settlement The net periodic benefit or expense for defined benefit pension plans excluding the early retirement program and special separation benefit expense, curtailment, settlement and other programs separately disclosed in the financial statements. New Accounting Principles, Early Adoption [Domain] New Accounting Principles, Early Adoption [Domain] Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] Entity Shell Company Entity Shell Company Segment Reporting Information [Line Items] Business Segments [Line Items] Segment Reporting Information [Line Items] Fair Value, Recurring [Member] Fair Value, Recurring [Member] Document Type Document Type After June 30, 2048 [Member] After June 30, 2048 [Member] Period of time after June 30, 2048 (thirtieth year) for which the TOSA term applies Other income, net Total Other Non-Operating Income Other income, net Other Nonoperating Income (Expense) Acquisition of redeemable noncontrolling interest Acquisition of Redeemable Noncontrolling Interest The fair value of the creation of a redeemable noncontrolling interest due to the acquisition of less than 100% of an entity. Treasury Stock [Member] Treasury Stock [Member] Accounts payable and accrued liabilities Increase (Decrease) in Accounts Payable and Accrued Liabilities Amortization Of Intangible Assets And Impairment of Goodwill and Other Long-Lived Assets Amortization Of Intangible Assets And Impairment of Goodwill and Other Long-Lived Assets Amortization Of Intangible Assets And Impairment of Goodwill and Other Long-Lived Assets Revenue Remaining Performance Obligation Percentage of Revenue Expected to be Recognized Over Next 12 Months Revenue Remaining Performance Obligation Percentage of Revenue Expected to be Recognized Over Next 12 Months Revenue Remaining Performance Obligation Percentage of Revenue Expected to be Recognized Over Next 12 Months Period of Transition Operations and Support Agreement [Axis] Period of Transition Operations and Support Agreement [Axis] Period of Transition Operations and Support Agreement [Axis] Segments [Axis] Segments [Axis] Pension and Postretirement Plans Retirement Benefits [Text Block] Summary of Changes in Accumulated Other Comprehensive Income (Loss) Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Schedule of Restructuring and Related Costs [Table] Schedule of Restructuring and Related Costs [Table] Level 3 Fair Value, Inputs, Level 3 [Member] Restructuring Cost and Reserve [Line Items] Restructuring Cost and Reserve [Line Items] Deferred Income Taxes Deferred Income Tax Liabilities, Net Defined benefit plan, target allocation maximum percentage of assets, singular equity security, without prior approval by plan administrator Defined Benefit Plan Target Allocation Percentage Of Assets Singular Equity Security Limit Without Approval Of Plan Administrator Target allocation maximum percentage of investment in a single equity security to total plan assets without prior approval of plan administrator. Issuance of borrowings Proceeds from Issuance of Debt Schedule of Prospective Adoption of New Accounting Pronouncements Schedule of Prospective Adoption of New Accounting Pronouncements [Table Text Block] Trade Names and Trademarks [Member] Trademarks and Trade Names [Member] Deferred revenue Deferred Revenue, Current Income from Operations Income (Loss) from Operations Operating Income (Loss) Professional (U.S.) [Member] Professional (U.S.) [Member] Professional (U.S.) [Member] Severance Severance Costs Commercial note [Member] Commercial note with SunTrust [Member] Commercial Note With SunTrust [Member] Contract with Customer, Liability Contract with Customer, Contract Asset, Contract Liability, and Receivable [Table Text Block] Calculated under Revenue Guidance in Effect before Topic 606 [Member] Calculated under Revenue Guidance in Effect before Topic 606 [Member] Variable Rate [Axis] Variable Rate [Axis] Gain on acquiring a controlling interest in an equity affiliate Business Combination, Step Acquisition, Equity Interest in Acquiree, Remeasurement Gain Schedule of Business Acquisitions, by Acquisition [Table] Schedule of Business Acquisitions, by Acquisition [Table] Acquisition of noncontrolling interest Noncontrolling Interest, Increase from Business Combination Common shares repurchased Payments for Repurchase of Common Stock Entity Address, State or Province Entity Address, State or Province Other Comprehensive Income (Loss), Before Tax Other Comprehensive Income (Loss), before tax Other Comprehensive Income (Loss), before Tax Foreign currency exchange rate changes Goodwill, Foreign Currency Translation Gain (Loss) Auto dealerships [Member] Auto dealerships [Member] Auto dealerships Genesis [Member] Genesis [Member] Genesis [Member] Retained earnings Retained Earnings (Accumulated Deficit) Lease Right-of-Use Assets Operating Lease, Right-of-Use Asset Residential Healthcare [Member] Residential Healthcare Group Inc [Member] Residential Healthcare Group Inc [Member] Accounting Standards Update 2016-01 [Member] Accounting Standards Update 2016-01 [Member] Money Market Investments Money Market Funds, at Carrying Value Guaranteed Return Guaranteed Return Preferred annual return on portfolio investments guaranteed to the Company Property, plant and equipment Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment Common Stockholders’ Equity Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Average borrowings outstanding Average Outstanding Debt Amount Average borrowings outstanding during the period, both short and long term. Noncontrolling interest purchased Noncontrolling Interest Purchased Percent of noncontrolling interest purchased during the period. Other Payments for (Proceeds from) Other Investing Activities Separation Incentive Program [Member] Separation Incentive Program [Member] Separation Incentive Program [Member] Amortization of unearned stock compensation and stock option expense APIC, Share-based Payment Arrangement, Increase for Cost Recognition Difference between Revenue Guidance in Effect before and after Topic 606 [Member] Difference between Revenue Guidance in Effect before and after Topic 606 [Member] Number of television broadcast stations Number Of Television Broadcast Stations Owned Number of television broadcast stations owned by the Company. Length of accreditation term reaffirmed Accreditation Term Reaffirmed The length of the accreditation reaffirmed by the HLC. Inventory [Line Items] Inventory [Line Items] Business Acquisition [Axis] Business Acquisition [Axis] Costs amortized during the period Capitalized Contract Cost, Amortization Geographical [Domain] Geographical [Domain] Accumulated other comprehensive income, net of tax Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract] Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] York Joint Venture [Member] York Joint Venture [Member] York Joint Venture [Member] Number of pending program reviews Number of pending program reviews Number of pending program reviews. Gain on marketable equity securities and cost method investments, net Unrealized Gain (Loss) on Investments Contract with Customer, Duration [Domain] Contract with Customer, Duration [Domain] Schedule of Non-Operating Income (Expense) [Line Items] Schedule of Non-Operating Income (Expense) [Line Items] [Line Items] for Schedule of Non-Operating Income (Expense) [Table] Residential Hospice Illinois [Member] Residential Hospice Illinois [Member] Residential Hospice Illinois [Member] Fair value of debt instrument Debt Instrument, Fair Value Disclosure After June 30, 2027 [Member] After June 30, 2027 [Member] Period of time after June 30, 2027 for which the TOSA term applies Deferred compensation plan liabilities Deferred Compensation Liability, Current and Noncurrent Operating loss of acquired companies since acquisition date Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Provision for doubtful trade and other receivables Provision For Doubtful Trade And Other Receivables The amounts of provision for doubtful trade and other receivables. Intersubsegment Eliminations [Member] Intersubsegment Eliminations [Member] Amount Borrowed to Finance Business Acquisition Amount Borrowed to Finance Business Acquisition Amount Borrowed to Finance Business Acquisition Selling, General and Administrative Expenses [Member] Selling, General and Administrative Expenses [Member] Goodwill [Roll Forward] Goodwill [Roll Forward] Current and noncurrent lease liabilities Business Combination, Recognized Identifiable Asset Acquired and Liabiity Assumed, Current and Noncurrent Lease Liabilities Amount of current and noncurrent lease liabilities assumed in business combination Acqusitions and Dispositions [Abstract] Acqusitions and Dispositions [Abstract] Acqusitions and Dispositions [Abstract] Summary of Earnings Per Share, Basic and Diluted Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Capital Contributor [Domain] Capital Contributor [Domain] [Domain] for Capital Contributor [Axis] Concentration In Single Entity, Type Of Industry, Foreign Country Or Individual Fund [Member] Concentration In Single Entity, Type Of Industry, Foreign Country Or Individual Fund [Member] Concentration In Single Entity, Type Of Industry, Foreign Country Or Individual Fund [Member] Non-cash accretion on contingent consideration Accretion Expense Schedule of assets acquired and liabilities assumed Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block] Line of credit facility outstanding Credit facility Long-term Line of Credit Inventory Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Inventory Cash flow hedges AOCI, Cash Flow Hedge, Cumulative Gain (Loss), after Tax Long-term Contract with Customer [Member] Long-term Contract with Customer [Member] Defined Benefit Plan, Plan Assets, Category [Axis] Defined Benefit Plan, Plan Assets, Category [Axis] Net Cash Provided by Operating Activities Net Cash Provided by (Used in) Operating Activities Percentage of Shares Eligible to be Redeemed Percentage of Shares Eligible to be Redeemed Percentage of share minority shareholders may put to the Company through redeemable noncontrolling interest Entity Central Index Key Entity Central Index Key CSI Pharmacy Holding Company, LLC [Member] [Member] CSI Pharmacy Holding Company, LLC [Member] [Member] CSI Pharmacy Holding Company, LLC [Member] [Member] Capital Contributor [Axis] Capital Contributor [Axis] Capital Contributor [Axis] Credit facility current borrowing capacity Line of Credit Facility, Current Borrowing Capacity Cash Flow Hedges [Member] Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Net (income) loss attributable to noncontrolling interest Noncontrolling Interest in Net Income (Loss) Other Noncontrolling Interests, Nonredeemable Income taxes receivable Income Taxes Receivable Income Taxes Receivable, Current Geographical [Axis] Geographical [Axis] Cumulative undistributed income in investments in affiliates Retained Earnings, Undistributed Earnings from Equity Method Investees Reclassification from AOCI, Current Period, Tax Provision for Income Tax Reclassification from AOCI, Current Period, Tax Medicare Accelerated Advanced Payment Program Relief Fund [Member] Medicare Accelerated Advanced Payment Program Relief Fund [Member] Medicare Accelerated Advanced Payment Program Relief Fund under the CARES Act Segments [Domain] Segments [Domain] Non-operating pension and postretirement benefit income, net Net Periodic Defined Benefits Expense (Reversal of Expense), Excluding Service Cost Component Amount of Revenue Recognized From Provider Relief Fund Amount of Revenue Recognized From Provider Relief Fund Amount of revenue recognized from provider relief fund Sale of KHE Campuses business [Member] Sale Of KHE Campuses Business [Member] Sale of KHE Campuses business [Member] Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Pro Forma Net Income Business Acquisition, Pro Forma Net Income (Loss) Income Statement Location [Axis] Income Statement Location [Axis] Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Indefinite-Lived Intangible Assets [Line Items] Indefinite-lived Intangible Assets [Line Items] Total pension and other postretirement plans, before tax Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax Derivative, Notional Amount Derivative, Notional Amount Amortization of intangible assets Amortization of Intangible Assets Amortization of Intangible Assets CableONE [Member] Cable One [Member] Cable One [Member] Business Segments Segment Reporting Disclosure [Text Block] Acquisition of redeemable noncontrolling interest Equity Effect of Acquisition of Redeemable Noncontrolling Interest Equity effect of acquisition of redeemable noncontrolling interest Number of Stores Number of Stores Title of 12(b) Security Title of 12(b) Security Gain (loss) on marketable equity securities, net Gain (loss) on marketable equity securities, net Equity Securities, FV-NI, Gain (Loss) Amortized Intangible Assets, Net Net Carrying Amount Finite-Lived Intangible Assets, Net Percentage of Contributed Capital Percentage of Contributed Capital Percentage of Contributed Capital Income taxes payable Accrued Income Taxes, Current Prepaid Pension Cost Assets for Plan Benefits, Defined Benefit Plan Interest expense Interest expense Interest Expense Other Stockholders' Equity, Other Depreciation and amortization Depreciation, Depletion and Amortization Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners Schedule of New Accounting Pronouncements and Changes in Accounting Principles Accounting Standards Update and Change in Accounting Principle [Table Text Block] Product and Service [Axis] Product and Service [Axis] Net Prior Service (Credit) Cost [Member] Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent [Member] Transferred at Point in Time [Member] Transferred at Point in Time [Member] Other indebtedness Other Long-term Debt Non-US [Member] Non-US [Member] Identifiable Assets Identifiable Assets Identifiable assets by segment are those assets used in the Company's operations in each business segment. Deferred revenue recognized in period related to beginning balance Contract with Customer, Liability, Revenue Recognized Numerator for basic earnings per share Net Income (Loss) Available to Common Stockholders, Basic Fair Value, Recurring and Nonrecurring [Table] Fair Value, Recurring and Nonrecurring [Table] Raw materials Inventory, Raw Materials, Net of Reserves Network Affiliation Agreements [Member] Contract-Based Intangible Assets [Member] Timing of Transfer of Good or Service [Domain] Timing of Transfer of Good or Service [Domain] Debt Instrument [Axis] Debt Instrument [Axis] Operating Segments [Member] Operating Segments [Member] Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Repurchase of Class B Common Stock Treasury Stock, Value, Acquired, Cost Method Adjustments to reconcile net income to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Revenue from Contract with Customer [Abstract] Revenue from Contract with Customer [Abstract] Schedule of Investments [Line Items] Schedule of Investments [Line Items] Number of Restaurants Number of Restaurants Other Asset Impairment Charges Other Asset Impairment Charges Subsequent Event [Member] Subsequent Event [Member] Net income attributable to redeemable noncontrolling interests Temporary Equity, Net Income Concentration Risk Type [Axis] Concentration Risk Type [Axis] Accounts and Financing Receivable, after Allowance for Credit Loss [Abstract] Accounts and Financing Receivable, after Allowance for Credit Loss [Abstract] Pension and other post retirement benefits liabilities Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Pension and Other Post Retirement Benefits Liabilities Amount of pension and postretirement liabilities assumed at the acquisition date. Initial Application Period Cumulative Effect Transition [Domain] Initial Application Period Cumulative Effect Transition [Domain] Applicable Years [Domain] Applicable Years [Domain] [Domain] for Applicable Years [Axis] Purdue University Global Final Payment Note Duration Purdue University Global Final Payment Note Duration Duration of note for final payment made by Purdue University Global to Kaplan upon termination of TOSA Foreign exchange swap Foreign Currency Contracts, Liability, Fair Value Disclosure Loan Receivable Fixed Interest Rate Related Party Transaction, Rate Other current investments Other Short-term Investments Gain on disposition of businesses, property, plant and equipment and investments, net Gain (Loss) on Disposition of Assets Lease Liabilities Operating Lease, Liability, Noncurrent Estimated amortization of intangible assets, 2024 Finite-Lived Intangible Asset, Expected Amortization, Year Four Hometown Home Health and Hospice [Member] Hometown Home Health and Hospice [Member] Hometown Home Health and Hospice Proceeds from (repayments of) bank overdrafts Proceeds from (Repayments of) Bank Overdrafts Pinnacle Bank Line Of Credit [Member] Pinnacle Bank Line Of Credit [Member] Pinnacle Bank line of credit [Member] Amortized intangible assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles First Five Years of Transition and Operations Support Agreement First Five Years of Transition and Operations Support Agreement First five years of TOSA Current Assets Assets, Current [Abstract] Goodwill expected to be deductible for income tax purposes Business Acquisition, Goodwill, Expected Tax Deductible Amount Interest income Investment Income, Interest Education, Code3 and Decile [Member] Education, Code3 and Decile [Member] Education, Code3 and Decile businesses. Total Financial Assets Investments, Fair Value Disclosure 5.75% Unsecured Notes due June 1, 2026 [Member] Five Point Seven Five Percent Unsecured Notes due June 1, 2026 [Member] Five Point Seven Five Percent Unsecured Notes due June 1, 2026 [Member] Franchise Agreements [Member] Franchise Rights [Member] International equities [Member] Defined Benefit Plan, Equity Securities, Non-US [Member] Goodwill, beginning balance Goodwill, ending balance Goodwill, Gross Subsegments [Domain] Subsegments [Domain] Total Comprehensive Income Attributable to Graham Holdings Company Comprehensive Income (Loss), Net of Tax, Attributable to Parent Translation adjustments arising during the period Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss), before Reclassification and Tax Legal Entity [Axis] Legal Entity [Axis] City Area Code City Area Code Healthcare [Member] Health Care [Member] Document Period End Date Document Period End Date Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Advances to Affiliate Advances to Affiliate Net Income Net Income Net income (loss) for the period Net of Tax Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Percentage of Cost Efficiencies Percentage of Cost Efficiencies Percentage of Cost Efficiencies to be used to Calculate Additional Efficiency Payment Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax Net amount reclassified from accumulated other comprehensive income (loss) Reclassifications, net of tax Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax Accounts receivable, net Accounts receivable, net Accounts and Other Receivables, Net, Current Business Combination, Step Acquisition, Equity Interest in Acquiree, Including Subsequent Acquisition, Percentage Business Combination, Step Acquisition, Equity Interest in Acquiree, Including Subsequent Acquisition, Percentage Other Comprehensive Income (Loss), before Reclassifications, before Tax Other Comprehensive Income (Loss), before Reclassifications, before Tax Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Stock-based compensation expense, net Share-based Payment Arrangement, Noncash Expense Redeemable noncontrolling interest Business Combination Acquisition Of Less than 100 Percent Redeemable Noncontrolling Interest Fair Value This element represents the fair value of the redeemable noncontrolling interest in the acquiree at the acquisition date. CSI Pharmarcy [Member] CSI Pharmarcy [Member] CSI Pharmarcy [Member] Other Proceeds from (Payments for) Other Financing Activities Carrying value of debt instrument Unsecured notes Unsecured Debt Cover [Abstract] Cover [Abstract] Percentage of Revenue After Kaplan Efficiency Payment Percentage of Revenue Remaining To Be Paid Percentage of Purdue University Global Revenue remaining after Kaplan Efficiency Payment and other adjustments paid to Purdue University Global U.S. fixed income [Member] Fixed Income Securities, US [Member] Investment that provides a return in the form of fixed periodic payments and eventual return of principal at maturity, domiciled in United States of America (US). Other Comprehensive Income (Loss), before Reclassifications, Net of Tax Other comprehensive loss before reclassifications Other Comprehensive Income (Loss), before Reclassifications, Net of Tax Income Taxes [Table] Income Taxes [Table] -- None. No documentation exists for this element. -- Other Comprehensive Income (Loss) [Table] Other Comprehensive Income (Loss) [Table] Other Comprehensive Income (Loss) [Table] Fixed income securities [Member] Fixed Income Securities [Member] Schedule of Non-Operating Income (Expense) [Table] Schedule of Non-Operating Income (Expense) [Table] Schedule of Non-Operating Income (Expense) [Table] Recipient of Consideration [Domain] Recipient of Consideration [Domain] [Domain] for Recipient of Consideration Loan Receivable, Payment Terms Loan Receivable, Payment Terms Description of the payment terms of the debt instrument (for example whether periodic payments include principal and frequency of payments) and discussion about any contingencies associated with the payment. Value of investments Investments Percentage of joint venture sold Percentage Of Joint Venture Sold The percentage of a joint venture sold. Service cost Pension Service Cost Defined Benefit Plan, Service Cost Other Non-Operating Income Other Income and Other Expense Disclosure [Text Block] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Student and Customer Relationships [Member] Customer Relationships [Member] Total Operating Costs and Expenses Costs and Expenses Equity Components [Axis] Equity Components [Axis] Number of existing legal claims or proceedings that are likely to have a material effect on the Company's business Loss Contingency, Pending Claims, Number Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Net borrowing under revolving credit facilities Proceeds from (Repayments of) Lines of Credit Minimum [Member] Minimum [Member] Amount Paid Entitled To Recover Amount Paid Entitled To Recover The amount paid the Company believes it is entitled to recover. Heverald [Member] Heverald [Member] Heverald [Member] Current Deferred Revenue [Member] Current Deferred Revenue [Member] Current deferred revenue [Member] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Equity Method Investment Impairment Equity Method Investment, Other than Temporary Impairment Income Tax Authority, Name [Domain] Income Tax Authority, Name [Domain] Defined Benefit Plan, Plan Assets, Category [Domain] Defined Benefit Plan, Plan Assets, Category [Domain] Net (Income) Loss Attributable to Noncontrolling Interests Net Income (Loss) Attributable to Noncontrolling Interest Recognized actuarial loss (gain) Defined Benefit Plan, Amortization of Gain (Loss) Contract with Customer, Asset, Net, Noncurrent Contract with Customer, Asset, after Allowance for Credit Loss, Noncurrent Licensure and Accreditation [Member] Licensure and Accreditation [Member] Licensure And Accreditation [Member] Entity Interactive Data Current Entity Interactive Data Current U.S. [Member] UNITED STATES Net pension benefit and special separation benefit expense Net Periodic Cost (Benefit) Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Schedule of Allocation of Plan Assets Schedule of Allocation of Plan Assets [Table Text Block] Cash Flows from Operating Activities Net Cash Provided by (Used in) Operating Activities [Abstract] Alphabet and Berkshire Hathaway Common Stock [Member] Alphabet And Berkshire Hathaway Common Stock [Member] Alphabet and Berkshire Hathaway Common Stock [Member] Estimated amortization of intangible assets, remainder of 2020 Finite-Lived Intangible Asset, Expected Amortization, Remainder of Fiscal Year Kaplan International [Member] Kaplan International [Member] Kaplan International [Member] Unusual or Infrequent Item, or Both [Axis] Unusual or Infrequent Item, or Both [Axis] Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Percent of plan assets managed internally by the company Percent of Plan Assets Managed Internally by Company The percentage of plan assets managed internally by the Company. Schedule of Investments [Table] Schedule of Investments [Table] Information related to Disposal Group Schedule Of Disposal Groups Excluding Discontinued Operations Income Statement Balance Sheet And Additional Disclosures [Table Text Block] Tabular disclosure of information related to a disposal group. Excludes a discontinued operation, disposal classified as held-for-sale or disposed of by means other than sale or disposal of an individually significant component. Percentage of Revenue Percentage of Revenue from Contract with Customer, Excluding Assessed Tax Percentage of Revenue Recognized During Period from Contract with Customer, Excluding Assessed Tax Number of reportable segments Number of Reportable Segments Contingent Consideration settlement Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability Other Nonoperating Income (Expense) [Abstract] Other Nonoperating Income (Expense) [Abstract] Single Equity Concentration [Member] Single Equity Concentration [Member] Information about an entity's defined benefit plan's significant investment concentrations in either a single entity, type of industry, foreign country and/or individual fund. Retirement Plan Type [Domain] Retirement Plan Type [Domain] Weighted average restricted stock Antidilutive Restricted Stock Additional shares excluded in the calculation of diluted EPS as a result of the antidilutive effect of restricted stock using the treasury stock method. Consolidation Items [Axis] Consolidation Items [Axis] Impairment Goodwill, Impairment Loss Receivable from contracts with customers, less estimated credit losses Accounts Receivable, after Allowance for Credit Loss, Current Gross unrealized losses EquitySecuritiesFVNIAccumulatedGrossUnrealizedLoss Amount of unrealized loss on investment on equity security measured at fair value with change in fair value recognized in net income (FV-NI). March 22, 2018 through June 30, 2022 [Member] March 22, 2018 through June 30, 2022 [Member] Period of time March 22, 2018 through June 30, 2022 for which the TOSA term applies (first 4 years) Unrealized gain on pensions and other postretirement plans Accumulated Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax Percentage Ownership After Change in Noncontrolling Interest Ownership percentage by parent Noncontrolling Interest, Ownership Percentage by Parent Foreign currency translation adjustments: Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax, Portion Attributable to Parent [Abstract] Equity in losses (earnings) of affiliates, net of distributions Income (Loss) from Equity Method Investments, Net of Dividends or Distributions Income taxes receivable Increase (Decrease) in Income Taxes Document Transition Report Document Transition Report Level 2 Fair Value, Inputs, Level 2 [Member] Document Quarterly Report Document Quarterly Report Derivative, Fixed Interest Rate Fixed interest rate of derivative Derivative, Fixed Interest Rate Loans Payable to Bank Loans Payable to Bank Basic net income per common share in dollars per share Basic income per common share in dollars per share Earnings Per Share, Basic Group of Senior Managers of GHG [Member] Group of Senior Managers of GHG [Member] Group of Senior Managers of GHG [Member] Schedule of Indefinite-Lived Intangible Assets [Table] Schedule of Indefinite-Lived Intangible Assets [Table] Entity File Number Entity File Number Other Comprehensive Income (Loss) [Line Items] Other Comprehensive Income (Loss) [Line Items] [Line Items] for Other Comprehensive Income (Loss) [Table] Curtailment gain Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Curtailment Supplemental Executive Retirement Plan (SERP) [Member] Supplemental Employee Retirement Plan [Member] Graham Holdings Company [Member] Graham Holdings Company [Member] Graham Holdings Company [Member] Issuance of noncontrolling interest Proceeds from Noncontrolling Interests Dividends on common stock Dividends, Common Stock Number of investments the company's pension plan held which individually exceed 10% of total plan assets Number Of Investments Companys Pension Plan Held Which Individually Exceed 10 Percent Of Total Plan Assets Number Of Investments The Companys Pension Plan Held Which Individually Exceed 10 Percent Of Total Plan Assets Defined Benefit Plan Assets Total [Member] Defined Benefit Plan Assets Total [Member] -- None. No documentation exists for this element. -- Balance Sheet Location [Axis] Balance Sheet Location [Axis] Goodwill and Intangible Assets Disclosure [Abstract] Goodwill and Intangible Assets Disclosure [Abstract] Accelerated depreciation Accelerated Depreciation Amount of accelerated depreciation charged against earnings. Intangible asset impairment charge Impairment of Intangible Assets, Finite-lived Schedule of Accounts Receivable Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] Number of Consecutive Years of Purdue University Global Cash Operating Losses Number of Consecutive Years of Purdue University Global Cash Operating Losses Number of consecutive years of Purdue University Global cash operating losses for option to terminate Transition and Operations Support Agreement Weighted average interest rate Debt Instrument, Interest Rate During Period Noncontrolling Interest Stockholders' Equity Attributable to Noncontrolling Interest Cash Flows from Investing Activities Net Cash Provided by (Used in) Investing Activities [Abstract] Change in capitalized contract cost, other Change in Capitalized Contract Cost, Other Change in capitalized contract cost, other Schedule of Defined Benefit Plans Disclosures [Table] Schedule of Defined Benefit Plans Disclosures [Table] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Accounts receivable, net Increase (Decrease) in Accounts Receivable Interest rate swap Interest Rate Cash Flow Hedge Liability at Fair Value Statement of Comprehensive Income [Abstract] Statement of Comprehensive Income [Abstract] Investment Managers [Domain] Investment Managers [Domain] [Domain] for Investment Managers [Axis] Concentration Risk Type [Domain] Concentration Risk Type [Domain] Test Preparation [Member] Test Preparation [Member] Test Preparation [Member] Total Liabilities and Equity Liabilities and Equity Loss Contingencies [Line Items] Loss Contingencies [Line Items] Number of businesses acquired Number of Businesses Acquired Income Taxes Income Tax Disclosure [Text Block] Manufacturing [Member] Manufacturing [Member] Manufacturing business Other liabilities Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities Antidilutive securities, shares Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Borrowing capacity Vehicle Floor Plan Facility Borrowing Capacity The aggregate borrowing capacity under the vehicle floor plan facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facilities. Investments in Marketable Equity Securities Marketable Securities [Table Text Block] Useful Life Finite-Lived Intangible Asset, Useful Life Equity Component [Domain] Equity Component [Domain] Property, Plant and Equipment, Net Property, Plant and Equipment, Net Entity Tax Identification Number Entity Tax Identification Number Accrued Compensation and Related Benefits Deferred Compensation Liability, Classified, Noncurrent Net Income Attributable to Graham Holdings Company Common Stockholders Net income attributable to Graham Holdings Company common stockholders Net Income (Loss) Attributable to Parent Investments in equity affiliates and cost method investments Payments To Acquire Equity Method And Cost Method Investments The cash outflow associated with the purchase of equity method investments, which are investments in joint ventures and entities in which the entity has an equity ownership interest normally of 20 to 50 percent and exercises significant influence or cost method investments. Change in operating assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] Inventories, Contracts in Progress and Vehicle Floor Plan Payable Inventory Disclosure [Text Block] Current Fiscal Year End Date Current Fiscal Year End Date Private investment fund [Member] Private Equity Funds [Member] Early Retirment Program Expense [Axis] Early Retirment Program Expense [Axis] -- None. No documentation exists for this element. -- Prior Period Reclassification Adjustment Prior Period Reclassification Adjustment Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Previous Accounting Guidance [Member] Previous Accounting Guidance [Member] Estimated amortization of intangible assets, after 2024 Finite-Lived Intangible Asset, Expected Amortization, after Year Four Amount of amortization for asset, excluding financial asset and goodwill, lacking physical substance with finite life expected to be recognized after fourth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). Impairment of goodwill and other intangible assets Goodwill and Intangible Asset Impairment Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] Loss contingency, estimate of possible loss Loss Contingency, Estimate of Possible Loss U.S. equities [Member] Defined Benefit Plan, Equity Securities, US [Member] Net income attributable to redeemable noncontrolling interests Net Income (Loss) Attributable to Redeemable Noncontrolling Interest Monthly installment payments Debt Instrument, Periodic Payment, Principal Joyce/Dayton Corp. [Member] Joyce/Dayton Corp. [Member] Joyce/Dayton Corp. [Member] Reclassification out of Accumulated Other Comprehensive Income [Table] Reclassification out of Accumulated Other Comprehensive Income [Table] Income tax (expense) benefit related to items of other comprehensive income (loss) Other Comprehensive Income (Loss), income tax Other Comprehensive Income (Loss), Tax Gross Carrying Amount Finite-Lived Intangible Assets, Gross Contracts in progress Inventory for Long-term Contracts or Programs, Gross New Accounting Pronouncement, Early Adoption [Line Items] New Accounting Pronouncement, Early Adoption [Line Items] CARES Act relief from COVID-19 [Member] CARES Act relief from COVID-19 [Member] CARES Act relief from COVID-19 New Accounting Pronouncement, Early Adoption [Axis] New Accounting Pronouncement, Early Adoption [Axis] Net (payments) proceeds from vehicle floor plan payable Proceeds From (Payments Of) Vehicle Floor Plan Payable Net The net cash inflow or cash outflow from proceeds or repayment of the vehicle floor plan payable. Provision for doubtful trade receivables Credit loss expense Accounts Receivable, Credit Loss Expense (Reversal) Transaction [Axis] Transaction [Axis] Transaction [Axis] Basic average number of common shares outstanding in shares Weighted average shares outstanding (shares) Weighted Average Number of Shares Outstanding, Basic Applicable interest rate margin Debt Instrument, Basis Spread on Variable Rate Net proceeds from disposition of businesses, property, plant and equipment, investments and other assets Net Proceeds From Sale Of Businesses Property Plant And Equipment And Other Assets The cash inflow associated with the amount received from the sale of a portion of the company's business, for example a segment, division, branch or other business, during the period. Also included is the cash inflow from the sale of long-lived, physical assets and other assets. Investments in Affiliates Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures Ownership [Axis] Ownership [Axis] Increase (Decrease) in Temporary Equity [Roll Forward] Increase (Decrease) in Temporary Equity [Roll Forward] Hoover Treated Wood Products [Member] Hoover Treated Wood Products [Member] Hoover Treated Wood Products [Member] Loss Contingencies [Table] Loss Contingencies [Table] Loan to related party Payments for Advance to Affiliate Revenue from Contracts with Customers Revenue from Contract with Customer [Text Block] Ownership percentage of joint venture Equity Method Investment, Ownership Percentage Equity Method Investment, Ownership Percentage Amortization of net actuarial loss (gain) included in net income Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax Foreign exchange gain Foreign currency (loss) gain, net Foreign Currency Transaction Gain (Loss), before Tax Provision for Income Taxes Income Tax Expense (Benefit) Beginning Cash and Cash Equivalents and Restricted Cash Ending Cash and Cash Equivalents and Restricted Cash Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Change in redemption value of redeemable noncontrolling interest Change in redemption value of mandatorily redeemable noncontrolling interest Noncontrolling Interest, Change in Redemption Value Purchases of marketable equity securities Payments to Acquire Marketable Securities Payments to Acquire Marketable Securities Gain on sale of equity affiliates Equity Method Investment, Realized Gain (Loss) on Disposal Indefinite-lived Intangible Assets, Major Class Name [Domain] Indefinite-lived Intangible Assets, Major Class Name [Domain] Length of program review Length Of Full Review Of Student Files The length of a full review of student files. Local Phone Number Local Phone Number Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax Reclassifications, before tax Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax Acquisition Pro Forma Financial Information Business Acquisition, Pro Forma Information [Table Text Block] Commercial note with Truist Bank [Member] Commercial note with Truist Bank [Member] Commercial note with Truist Bank Revenues of acquired companies since acquisition date Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual Write-down of cost method investments Impairment of a cost method investment Impairment of cost method investments Equity Securities without Readily Determinable Fair Value, Impairment Loss, Annual Amount After June 30, 2024 [Member] After June 30, 2024 [Member] Period of time after June 30, 2024 (7th year and beyond) for which the TOSA term applies Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Schedule of Finite-Lived Intangible Assets [Table] Schedule of Finite-Lived Intangible Assets [Table] Schedule of Earnings Per Share, Basic and Diluted, Including Two Class Method [Table] Schedule of Earnings Per Share, Basic and Diluted, Including Two Class Method [Table] Disclosures pertaining to an entity's basic and diluted earnings per share. Line of Credit Facility, Maximum Borrowing Capacity Line of Credit Facility, Maximum Borrowing Capacity Award Type [Axis] Award Type [Axis] CARES Act Fund [Domain] CARES Act Fund [Domain] CARES Act Fund [Domain] Other noncurrent assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets After June 30, 2023 [Member] After June 30, 2023 [Member] Period of time after June 30, 2023 (6th year and beyond) for which the TOSA term applies Retained Earnings [Member] Retained Earnings [Member] Dispositions Goodwill, Written off Related to Sale of Business Unit Deferred payments of acquisition Payment for Contingent Consideration Liability, Financing Activities Foreign Investments [Member] Foreign Investments [Member] Information about the entity's defined pension plan foreign investments. Schedule of Net Benefit Costs Schedule of Net Benefit Costs [Table Text Block] Net Cash Provided by (Used in) Investing Activities Net Cash Provided by (Used in) Investing Activities Award Type [Domain] Award Type [Domain] Line of Credit Facility, Unused Capacity, Commitment Fee Percentage Line of Credit Facility, Unused Capacity, Commitment Fee Percentage Reportable Subsegments [Member] Reportable Subsegments [Member] Percent of plan assets managed by investment companies Percent Of Plan Assets Managed By Investment Companies The percentage of plan assets managed by investment companies. Cost of Class B common stock held in treasury Treasury Stock, Value Operating Operating Expense Generally recurring costs associated with normal operations including the portion of these expenses which can be clearly related to production and included in cost of sales or services. Excludes selling, general and administrative expenses. Defined Benefit Pension Plan [Member] Defined Benefit Pension Plans [Member] Pension Plan [Member] Earnings Per Share Earnings Per Share [Text Block] Retirement Benefits, Description [Abstract] Retirement Benefits, Description [Abstract] Redeemable Noncontrolling Interest As of As of Redeemable Noncontrolling Interest, Equity, Carrying Amount Current Liabilities Liabilities, Current [Abstract] Intersection Holdings [Member] Intersection [Member] Intersection Holdings,LLC [Member] Proceeds from Lines of Credit Proceeds from Lines of Credit Recently Adopted and Issued Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Subsegments [Axis] Subsegments [Axis]